Funds are requested in this proposal to purchase a JEOL JEM-1400 transmission electron microscope (TEM) to replace our aging, 21 year old Philips CM12S located in the Arizona Health Sciences Core Imaging Facility. The existing CM12S has increasing downtime for repairs with replacement parts becoming more difficult to obtain (FEI will only support the existing CM-12S for 30-36 months - see attached letter). The JEOL JEM-1400 will be the primary TEM available to basic and clinical researchers at the University of Arizona. Replacement of the aging microscope with a new TEM will insure that this technology is available to researchers at the University of Arizona for the foreseeable future. The JEOL JEM-1400 is a basic 120 kV TEM that meets the needs of our researchers. It is easy to use, has several digital imaging options and can be operated from remote locations. The instrument will support 8 NIH-funded major users who require the TEM for their research. Cellular and tissue ultra structural data collected using the JEOL JEM-1400 will be used to increase our understanding of colon and esophageal cancer, heart and muscle function and dysfunction, effects of toxicants during organ development, cardiovascular function, and immune function.